Ring-Opening Cyclization (ROC) of Aziridines with Propargyl Alcohols: Synthesis of 3,4-Dihydro‑2<i>H</i>‑1,4-oxazines

Activated aziridines react with propargyl alcohols in the presence of Zn(OTf)2 as the Lewis acid catalyst following an SN2-type ring-opening mechanism to furnish the corresponding amino ether derivatives. Those amino ethers further undergo intramolecular hydroamination via 6-exo-dig cyclization in the presence of Zn(OTf)2 as the catalyst and tetrabutylammonium triflate salt as an additive under one-pot two-step reaction conditions. However, for nonracemic examples, ring-opening and cyclization steps were conducted under two-pot conditions. The reaction works well without any additional solvents. The final 3,4-dihydro-2H-1,4-oxazine products were obtained with 13 to 84% yield and 78 to 98% enantiomeric excess (for nonracemic examples)

Synthesis, Characterization and Antibacterial Investigation of Mononuclear Copper (II) Complexes of Amine-phenolate Based Ligands

The antibacterial activities of two previously reported copper (II) coordination complexes [Cu(HL1)Cl2] and [Cu(HL2)Cl2], and the two new complexes [Cu(HL3)Cl2] and [Cu(HL4)Cl2], where HL1 is 2-(((pyridin-2-ylmethyl)amino)methyl)phenol, HL2 is 2-((benzyl(pyridine-2-ylmethyl)amino)methyl)phenol, HL3 is 2-(((pyridin-2-ylethyl)amino)methyl)phenol and HL4 is 2-(((pyridin-2-ylmethyl)(quinolin-2-ylmethyl)-amino)methyl)phenol were investigated using agar well plate diffusion assay. The ligands were characterized using elemental analysis, IR, 1H-NMR, 13C-NMR spectroscopy and thermal analysis. The corresponding copper (II) complexes of each ligand were synthesized and characterized using elemental analysis, FT-IR and UV-Visible spectroscopy, electronic spectra and magnetic moment measurements, and thermal analysis. Additionally, a thorough investigation of the copper complexes as potent drug candidates was performed using web-based software SwissADME to predict their physicochemical and pharmacokinetics properties. All copper complexes were stable to air and moisture and showed excellent stability up to 200 °C. Electronic spectra of all copper complexes in methanol consisted of single band at 14,490–15,260 cm−1 depicting ligand field excitation (Cu (II) d–d band). Ligands were completely ineffective on gram positive bacteria; HL1 and HL3 showed moderate to high activity at concentration range of 0.2–1 mg/ml. Copper complexes were found to exhibit moderate to high activity against bacteria as compared to the ligands. SwissADME analysis of all copper (II) complexes justified their candidature as potential candidate for pharmaceutical applications.</p

Design, Synthesis, and Applications of a Vanadium Complex: An Effective Catalyst for the Direct Conversion of Alcohols and Aldehydes to Esters

A novel bench-stable V-catalyst [(L2)­VIVO]­(ClO4) was synthesized and characterized by X-ray diffraction (XRD) analysis and FT-IR, UV–visible, and EPR spectroscopies, which confirmed its excellent catalytic activity. In application, aldehydes are rapidly converted into their corresponding esters without additives in a one-pot manner using a newly developed catalyst [(L2)­VIVO]­(ClO4) and H2O2 as a green oxidant. The developed method is compatible with a broad range of densely substituted aldehydes and allows for the facile preparation of aliphatic, aromatic, and heterocyclic esters, including esters derived from CD3OD, methanol, ethanol, iso-propanol, n-butanol, sec-butyl alcohol, and propargylic alcohol. Gratifyingly, numerous alcohols also directly converted to their corresponding esters in a one-pot manner. We disclose herein the direct conversion of two different functionalities (alcohols and aldehydes) into esters (33 examples) with satisfactory yields, showing the potential of the developed catalyst toward varied oxidative organic transformations in a one-pot manner

Exploration of Experimental, Theoretical, Molecular Docking, and Electronic Excitation Studies of Carboxylate-Appended (2-Pyridyl)Alkylamine Ligand^†

‘In this study, we employed density functional theory (DFT)/B3LYP method with a 6-311++G(d,p) basis set to analyze the infrared and UV spectra of a carboxylate-appended (2-pyridyl)alkylamine ligand. The FT-IR spectra were recorded within the range of 4000–500 cm-1. Geometrical parameters, energies, and wavenumbers were determined, and the fundamental vibrations were assigned based on the potential energy distribution (PED) of the vibrational modes. The UV spectrum of the compound was measured in various solvents, namely DMSO, CHCl3, and CH3OH. The 1H-NMR shifts were estimated using the GIAO method, and the results were compared to experimental spectra. To further investigate the electronic properties, including excitation energies, absorption wavelengths, and highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies, we employed the DFT/B3LYP approach. The degree of electron localization was assessed through analysis of the ELF diagram. Additionally, a molecular electrostatic potential (MEP) was generated, and a 3-D color representation was utilized to visualize reactive sites. Lastly, a biological study involving molecular docking was conducted using six different receptors in order to identify optimal ligand-protein interactions and assess drug similarities.’</p

Experimental Spectroscopic, Computational, Hirshfeld Surface, Molecular Docking Investigations on 1H-Indole-3-Carbaldehyde

1H-Indole-3-carbaldehyde (1H-I3A) was investigated experimentally by NMR (1H-NMR and 13 C-NMR in solution form), FT-Raman, FT-IR, UV-Visible and quantum chemically by DFT approach. 3 D and 2 D surface analysis was carried by Hirshfeld surface analysis. The B3LYP method and the 6-311++G(d,p) basis set were used to optimize the molecular structure and vibrational modes. Optimized binding parameters and experimental binding parameters are in good agreement. VEDA (Vibrational Energy Distribution analysis) successfully carried out and complete tasks for the distribution of potential energy. 1H-NMR and 13 C-NMR shifts were estimated with GIAO method and the results compared with experimental spectra. The TDDFT method and the PCM solvent model were used for the analysis of electronic properties such as UV-Vis (in the gas phase, methanol and DMSO) and compared with the experimental UV-Vis spectra. The HOMO/LUMO energy results underscore that sufficient charge transfer has taken place within the molecule. Studies of donor-acceptor connections were performed using NBO analysis. The MEP surface analysis was performed and charge distribution was demonstrated. The degree of relative localization of electrons was analyzed using the FLF diagram. The Fukui functional analysis to find possible points of attack for various substituents. Molecular electrostatic potential (MEP) was created and 3-D color representation shows reactive sites. Study of donor-acceptor interconnections were done via NBO analysis. The biological study like molecular docking was done with 7 different receptors to find the best ligand-protein interactions and drug similarities.</p

Experimental Spectroscopic, DFT, Molecular Docking, and Molecular Dynamics Simulation Investigations on m-Phenylenediamine (Monomer and Trimer)

The DFT approach has studied experimental spectroscopic molecular docking simulations of m-Phenylenediamine (m-PD) with quantum calculations. A molecular dynamics simulation is used to explore biomolecular stability. VEDA successfully carried out complete tasks for the distribution of potential energy. 1H-NMR and 13C-NMR shifts were assessed by the GIAO method, and results were compared with experimental spectra. TDDFT method and PCM solvent model were used to analyze electronic properties such as UV-Vis (in the gas phase, ethanol, and DMSO) and compared with the experimental UV-Vis spectra. The HOMO/LUMO energy results emphasize adequate charge transfer within the molecule. The electron excitation analysis was completed. Studies of donor-acceptor connections were performed using NBO analysis. The MEP surface analysis was carried out to show the charge distribution in the molecule. The degree of relative localization of electrons was analyzed using the ELF diagram. The Fukui functional analysis to find probable sites of attack by various substituents. Hirshfeld surface showed m-PD was stabilized primarily by forming H–H/H–N/C–H contacts. Biological studies like molecular docking were done with eight different receptors to find the best ligand-protein interactions. Molecular Dynamic Simulation was used to calculate the binding free energy of complex and to validate the inhibitory potency. This study helps in understanding the structural properties of compounds which in turn aids in elucidating the mechanism of a chemical reaction and helps in designing new reactions and catalysts. The main objective is to study structures and their properties by simulating chemical systems to provide accurate, reliable, and comprehensive data at an atomic level.</p

Synthesis, Characterization, Crystal Structure, Hirshfeld Surface, Electronic Excitation, Molecular Docking, and DFT Studies on 2-Amino Thiophene Derivative

Ethyl-2-amino-5,6,7,8-tetrahydro-4H-cyclo-hepta[b]thiophene-3-carboxylate (EACHT) has been synthesized, characterized via single-crystal X-ray diffraction at 293 K and investigated quantum chemically by DFT approach, surface analysis by Hirshfeld and spectrochemically by NMR (1H-NMR and 13C-NMR), FTIR, and UV–Visible. The compound crystallizes in monoclinic crystal system with P21/c space group with Z = 4, with following unit cell dimensions: a = 9.5956 (3) Å, b = 9.5607 (4) Å, c = 13.7226 (7) Å. To get the optimized structure which is base for all the other calculations (vibrational frequency, NBO, natural hybrid orbital, nonlinear optical, frontier molecular orbital, etc.), B3LYP method with 6-311++G(d,p) basis set was used. Complete potential energy distribution assignments were done successfully by VEDA. 1H-NMR and 13C-NMR shifts were estimated by GIAO method and results were compared with experimental spectra. TDDFT method and PCM solvent model was utilized for electronic property analysis such as UV–Vis (in gas phase, ethanol, and DMSO) and compared with the experimental UV–Vis spectra. The HOMO and LUMO energy results emphasize adequate charge transfer was happened within the molecule. NBO analysis MEP surface analysis electron localization function Diagram and Fukui function analysis were done. Hole and Electron density distribution maps were drawn in two different excited states of higher oscillatory strength with DMSO, MeOH as solvents. Docking with seven different receptors, and drug likeness was also carried out.</p

Copper(II) Monomer Bearing Phenolate-Based Ligand: Theoretical and Experimental Visions

Using protonated forms of tridentate phenol amine ligand 2-((benzyl(pyridine-2-ylmethyl)amino)methyl)phenol (HL) mononuclear copper(II) complex was synthesized. This ligand yielded mononuclear complex of composition [Cu(HL)Cl2] (1) which has been characterized by X-ray crystallography, UV–vis, and EPR measurements. Complex 1 shows axial spectra typical of d9 (dx2-y2 as ground state) configuration. Using DFT/B3LYP/LANL2DZ and 6-311++G(d,p) level of theory, structural optimization, electronic and vibrational characteristics of the ligand and complex were examined. The experimental and theoretical parameters are quite well aligned. The assignments of the vibrational frequencies were performed by potential energy distribution analysis by using VEDA program. Molecular electrostatic potential and frontier molecular orbitals analysis have been carried out to understand the molecule reactivity. A TD-DFT computation is also started to replicate the UV–vis absorption spectrum and to determine various essential electronic parameters such as the HOMO–LUMO gap energy and electronic transitions.</p

Dinuclear Phenoxo-Bridged Nickel(II) and Copper(II) Complexes of Phenolate-Based Tripodal Ligand: Theoretical and Experimental Insights

Three dinuclear complexes of composition [NiII2(L)2][ClO4]2 and [CuII2(L)2(OClO3)2].3H2O have been synthesized using a new tripodal ligand [(2-pyridyl)methyl](2-benzyl)-aminomethyl}-phenol (HL)], in its deprotonated form, providing a N2O donor set. Crystallographic analyses reveal that [CuII2(L)2(OClO3)2].3H2O has a diphenoxo-bridged structure. In [CuII2(L)2(OClO3)2].3H2O, each metal center is MIIN2O3-coordinated with a square-pyramidal environment for each copper(II) center. In this work, the molecular structure, harmonic vibrational frequencies and UV-Vis of [NiII2(L)2]2+ and [CuII2(L)2]2+ has been explored. With the help of density functional theory (DFT)/B3LYP techniques and LANL2DZ as a basis set, the ground-state molecule shape and vibrational frequencies were computed. The basic vibrations were allocated using the VEDA program to compute the potential energy distribution (PED) of the vibrational modes. The band gap energies of the title complexes ([NiII2(L)2]2+ and [CuII2(L)2]2+) are 3.21 eV and 1.59 eV, respectively, according to HOMO-LUMO energies. The maximal absorption wavelength and band gap energy of the title complexes were calculated theoretically using the UV absorption spectra. MEP analysis identifies electrophilic and nucleophilic sites. Hirshfeld surface analysis was used to characterize the 3D intermolecular interactions in ([NiII2(L)2]2+ and [CuII2(L)2]2+) of the crystal surface, whereas fingerprint plots were used to explain the 2D interactions. The biological activity of the complexes was investigated using molecular docking.</p